Process for the emergency interruption of the flow of melt in a gravity casting plant

ABSTRACT

In a gravity casting plant the melt is dammed up in a supply chamber up to a level which is higher than the level of the mouth of a casting nozzle. The melt flows from the supply chamber into an oblong equalization chamber and from this into the casting nozzle, and the flow of melt when operating the casting plant under normal conditions is controlled by a valve situated between the supply chamber and the equalization chamber. To avoid undesired outflow of melt from the casting nozzle at least the melt in the region of the mouth of the casting nozzle is cooled until same melt is solidified. A cooling member having an internal cooling system is provided on the nozzle to provide for the necessary cooling thereof.

United States Patent Tenner [4 Aug. 13, 1974 1 PROCESS FOR THE EMERGENCY3,121,769 2/1964 Horn 266/42 INTERRUPTION 0 THE F Q MELT 3,682,4528/1972 Berczynski.... 266/42 X 3,705,61 12 1972 Tcnner 164 155 IN AGRAVITY CASTING PLANT 3,709,477 l/l973 Baumer et a1. 266/42 [75]Inventor: Oskar Tenner, Rossatz nr.

Niederosterr, Austria [73] Assignee: GravicastPatentverwertungsgesellschaft m.b.H.

[22] Filed: Jan. 11, 1973 [21] Appl. No.: 322,627

[30] Foreign Application Priority Data Jan. 13, 1972 Austria 286/71 [52]US. Cl 222/1, 222/146 C, 266/42 [51] Int. Cl B22d 37/00 [58] Field ofSearch 222/146 C, 1, DIG. l5, 222/DIG. 4, DIG. 5, DIG. 20, 559; 164/155,337; 266/38, 42

[56] References Cited UNITED STATES PATENTS 673,556 5/1901 Hartman266/42 2,957,936 10/1960 Bugge 266/42 X Primary ExaminerRobert B. ReevesAssistant Examiner-David A. Scherbel Attorney, Agent, or FirmHill,Gross, Simpson, Van Santen, Steadman, Chiara & Simpson 5 7 ABSTRACT In agravity casting plant the melt is dammed up in a supply chamber up to alevel which is higher than the level of the mouth of a casting nozzle.The melt flows from the supply chamber into an oblong equalizationchamber and from this into the casting nozzle, and the flow of melt whenoperating the casting plant under normal conditions is controlled by avalve situated between the supply chamber and the equalization chamber.To avoid undesired outflow of melt from the casting nozzle at least themelt in the region of the mouth of the casting nozzle is cooled untilsame melt is solidifled. A cooling member having an internal coolingsystem is provided on the nozzle to provide for the necessary coolingthereof.

5 Claims, 2 Drawing Figures PROCESS FOR THE EMERGENCY INTERRUPTION OFTHE FLOW F MELT IN A GRAVITY CASTING PLANT SPECIFICATION This inventionrelates to a process and a device for the emergency interruption of theflow of melt in a gravity casting plant.

It is a well known method in casting apparatus to dam up the melt in asupply chamber and to let it flow by the influence of gravity,preferably through an oblong equalization chamber, into a casting nozzleadjoining the casting mould. The melt in the supply chamber is kept at alevel which is higher than the level of the mouth of the casting nozzleand a valve or closure is provided between the supply chamber and thecasting nozzle to control or interrupt the flow of melt, respectively.In such machines the melt flows to the casting nozzle due to theinfluence of the weight of the melt dammed up in the supply chamber, andthe flow pattern of the melt is tranquilized in the equalization chamberafter having passed the closure, so that the turbulences introduced intothe melt due to the influence of the valve or closure are tranquilizedor removed so that the melt enters the casting nozzle free ofturbulences. Within these machines, however, problems occur owing to thefact that in general the life of the valve or closure, which usuallyconsists of a stopper and nozzle, is relatively short. This is due tothe fact that the valve or closure or the devices used to operate it,e.g. a stopper rod, partly dip into the melt and partly protrude fromthe melt surface, which leads to an extremely high abrasion andpremature destruction or wear of these areas of the valve or closure oroperating devices which are only temporarily covered by the melt. Thisis on the one hand due to alternating temperature stresses and on theother hand to the chemical reaction between the atmosphere (oxygen) andthe materials of the melt, the slag, the valve or closure as well asperhaps the refractory lining of the supply chamber and the equalizationchamber. It is, therefore, inevitable to replace the closure or valvefrom time to time. When exchanging a stopper or a similar member withinthe known embodiment, it is necessary to lower the melt level in thesupply chamber to below the level of the mouth of the casting nozzle toprevent that upon opening of the valve or closure for the exchangeoperation the melt is driven out of the casting nozzle as a result ofthe pressure of the melt volume dammed up in the supply chamber. Aftercompletion of the exchange operation the melt has to be refilled intothe supply chamber up to the working level. This, however, leads toreactions between the materials of the melt, the slag, the refractorymaterials and the closure or valve elements respectively (stopper andnozzle) and the air and consequently to an unnecessary premature wear ofthe lining and of the valve or closure, which in turn results inconsiderably increased costs and idle times. Even if such reactionscould be prevented, considerable time is necessary to drain and refillthe melt, during which operation the machine is idle. This method ofchanging the stopper or any other valve or closure device, therefore, isaccompanied by long idle times and production losses as well as highmaterial wastes.

In such machines further problems may arise if a sudden destruction ofthe stopper or of the nozzle cooperating therewith arises or if aleakage occurs in the partition wall between supply chamber andequalization chamber or if a leakage in the support of the castingnozzle occurs. In such a case the melt flows out of the nozzle or aroundthe nozzle like a fountain, which constitutes a danger for the workingpersonnel. Besides, the outflowing melt may damage or destroy the plant.Especially when an automatic mould conveying system is used, such a meltoutflow may produce considerable damage requiring long repair times andthus entailing high production losses.

It is an object of the invention to provide for a method by means ofwhich the casting plant can be brought to a standstill for the exchangeof the valve or closure or if a leakage occurs at the areas describedabove without requiring the draining of the melt.in the supply chamberbelow the level of the mouth of the casting nozzle.

It is a further object of the invention to make a casting plant of thekind described above more reliable in operation so that the danger forthe working personnel is reduced.

It is another object of the invention to provide for a process for theemergency interruption of the flow of melt in a gravity casting plant,in which a reliable and quick shut-off of the flow of melt is achievedeven if the control means for normally controlling the flow of melt outof the supply or storage chamber into the casting nozzle is damaged orout of order.

The'process according to the invention essentially consists in coolingat least the melt in the region or zone of the mouth or outlet openingof the casting nozzle until the melt in this zone or region issolidified whereby the flow of melt through the casting nozzle isinterrupted independently from the control means used for normallycontrolling the flow of melt from the supply or storage chamber into thecasting nozzle or an equalization chamber, to which the casting nozzleis connected. Thus the problems indicated above are solved bysolidifying the melt in or at the casting nozzle by cooling theoutflowing melt and thus preventing an undesired leakage of the melt atthe casting nozzle independently from the control of the melt flowthrough the closure or valve serving for normally controlling the streamof melt out of the supply or storage chamber. Such a solidification ofthe melt flow in the range or zone of the casting nozzle can be donequickly and inexpensively thus permitting a repair or replacement of thevalve or closure without requiring any draining of the melt in thesupply or storage chamber. The invention can also be used with advantagein the case of a dangerous leakage of the support of the casting nozzleor of the separation or partition wall between supply chamber andequalization chamber, since it is easily possible to produceautomatically a cooling of the melt at or around the casting nozzle,whenever extremely high temperatures occur in the vicinity of thecasting nozzle. It is, eg very easy to determine immediately anundesired outflow of the melt at the casting nozzle or around it bymeans of temperature control means or temperature sensitive means of anysuitable type known to one skilled in the art, or to register aninadmissable decrease of the level of the melt in the supply or storagechamber by means of a level gauge or level sensing means of any suitablewell known type. These control or sensing means may be used to energizean automatic mechanism which initiates the cooling operation needed forthe solidification of the melt in or at the casting nozzle. Thus, thesafety of the plant is considerably increased, since in the case of asudden breakdown of the stopper or of a similar closure or valve memberan uncontrolled outflow of the melt from the casting nozzle is no longerpossible so that there can no longer be any damage to the plant or anydanger to the personnel. This results in a considerable increase of theproduction rate.

The cooling of the melt in the range of the casting nozzle could beachieved by spraying a cooling agent, e.g. water on to the nozzle. Sincethis, however, entails the danger of a formation of water vapour andoxyhydrogen gas, it is more advantageous to put a cooling closure memberon to the casting nozzle, whenever this is to be cooled. Thus, anyformation of oxyhydrogen gas and water vapour is prevented and there canbe no explosions within the plant area. In accordance with a preferredmethod according to the invention the outer side of the support of thecasting nozzle is also cooled, which has the advantage that leakages inthe range of the support of the casting nozzle are sealed by thesolidification of the melt in this area.

The inventive apparatus to carry out the method according to theinvention is based on a casting machine which comprises a supply orstorage chamber, a casting nozzle having an outlet opening and a controlmeans for controlling the flow of melt due to the influence of thegravity from the supply chamber to the casting nozzle. Based upon thisembodiment, the inventive device comprises a cooling device effective atleast on the region or zone of the casting nozzle. This cooling devicemay be formed according to the invention by a cooling closure member forthe casting nozzle, which can be removed, preferably lifted off, fromthe casting nozzle. A closure member may be a cooled cover or lid, acooled stopper, a cooled plate, etc. However, it is also possible to useuncooled elements, if, owing to their own heat capacity, they producethe necessary temperature reduction of the melt to achieve asolidification of the melt. Preferably, according to the invention thecooling cover of the casting nozzle covers the casting nozzle and thesurrounding area of the casting support member, in order to include thisarea, too, in the cooling range.

In accordance with a further development of the invention the coolingmechanism has a cooling system closed at least in the zone or region ofthe casting device with respect to the atmosphere, through which coolingsystem a stream of a cooling agent, e.g. water is conducted. Within sucha closed cooling system the cooling agent is not in contact with theatmosphere but is conducted e.g. by a closed piping system. Therefore,the cooling agent cannot react with the atmosphere. There is no problemto design a closed cooling system in such a way that enough heat isconducted away to prevent the formation of any oxyhydrogen gas. Besides,suitable thermo-elements can be provided which prevent a superheating ofthe cooling fluid or control the amount of the cooling fluid.

The cooling mechanism or device which acts upon the area of the castingnozzle becomes effective whenever the stopper or any other valve memberneeds to be exchanged or when there is an undesired outflow of the meltfrom the casting nozzle or from the adjoining areas of the nozzlesupport. Since the invention also works whenever the stopper member orany other valve member or closure member breaks down, this member can beused until such a breakdown occurs, which allows for longer intervalsbetween two succeeding exchanges of the stopper member or the like,compared with traditional apparatus.

If the machine or plant is to be put into operation again, e.g. after anexchange or repair of the damaged stopper member or after the repair ofleakages, the solidified melt is again liquified in the zone or regionof the casting nozzle. This can be done by various methods. First, thecooling, which had led to a solidification of the melt in the area ofthe casting nozzle, is removed or stopped. Then it is possible to knockout, for instance by means of hammer and chisel, a solidified plug inthe casting nozzle, if it is not too strong. Another possibilityconsists in melting such a plug from above by means of an oxygen lance,or another heating device, e.g. electric heating wires for the castingnozzle or its surrounding region. Finally, it is also possible toliquify the solidified melt by means of the effect of the heat of thefollowing melt present in the equalization chamber or supply chamberalone, particularly if heat losses are prevented in the zone of thecasting nozzle, e.g. by means of a heat insulating cover consisting ofasbestos or wool of kaolin, so that there is an accumulation of heat inor at the casting nozzle.

A schematic illustration of the apparatus or device according to theinvention is shown in the accompanying drawing. FIG. it shows a verticalsection through the apparatus, whereas FIG. 2 represents a sectionaccording to line II II.

The supply chamber 2 formed by a supply or storage container 1 is filledwith melt 3, e.g., metal or a synthetic resin or plastic material. Thelevel 4 of the melt 3 in the supply or storage chamber 2 is essentiallykept constant by a device (not shown) suitable for this purpose. Suchdevices are well known to one skilled in the art. A stopper rod 5plunges into the melt 3 and has at its bottom end a stopper 6 whichconstitutes the closure member for an opening 7 of a nozzle member 8,which is inserted into the bottom wall of the supply chamber 2. Theopening 7 connects the supply chamber 2 with an oblong hollowcylindrical equalization chamber 9, in which the flow pattern of themelt is tranquilized.

At its upper end the stopper rod 5 is fixed to a stopper support 10. Thestopper support 10 shows a cylindrical protrusion 11, which fits into abore 12 of the stopper rod 5 and is fixed thereto by means of a screw 13which intersects the stopper rod 5 and the protrusion 11. The stoppersupport 10 is vertically adjustable and is guided for upward anddownward movement by means of rollers 14. This movement is effected bymeans of a lever 15, which is pivotally mounted on a fixed swivel point16.

The member confining the equalization chamber 9, which member isconstituted, e.g., by an oblong pipe 17, is connected to a castingnozzle 18. In order to heat the melt in the equalization chamber 9, anywellknown suitable heating device (not shown) can be used, e.g., aninduction heating device which is connected with the equalizationchamber 9 by means of openings 19 in the wall of the pipe 17. Thecasting nozzle 18 has ducts 20 through which a cooling fluid, e.g.,water, can pass and/or through which electric resistance heating wires(not shown) run. Thus a cooling or heating of the casting nozzle can beachieved, so that the melt in it can be solidified or reliquified, as itis desired.

A console 21 is fixed to the wall of the supply chamber 1. To thisconsole 21 swivelling arm 23 is linked by means of a bolt 22 so thatthis arm 23 can be pivoted in a horizontal plane. A swivelling arm 25with a cooling member 26 at its end is fixed to arm 23 by means of apivot means 24, so that this arm 25 can be pivoted in a vertical plane.In its lowermost position shown in FIG. 1 by full lines, this coolingmember 26 is situated exactly above the casting nozzle 18. The coolingmember 26 has a protrusion 27, which entersinto the casting duct 28 ofthe casting nozzle 18 and on the one hand serves for centering thecooling member 26 from the casting nozzle 18 and on the other handserves to enhance the cooling effect on the casting nozzle 18. Due toits own heat capacity the cooling member 26 may have a cooling effect onthe melt in the casting duct 28 of the casting nozzle 18 or may containa builtin cooling system (not shown) to further intensify the coolingeffect. The cooling fluid, e.g., water, of this cooling system issupplied or sucked off, respectively, via the pipes 29.

In order to achieve the vertical swivelling motion of the cooling member26 a unit 30 formed by a hydraulic or pneumatic piston and a cylinder isprovided, which unit is journally mounted to a pivot 31 forked at oneend, which pivot is rigidly connected to the bolt 22. The piston rod 32aofthis unit 30 is pivotally connected by a joint to arm 25. Thus the arm25 and the cooling member 26 can be lifted to the position 25', 26'shown with dashed lines in FIG. 1, in which position the cooling member26 releases the casting nozzle 18 so that the casting nozzle is free forits usual purposes, e.g., filling a mould (not shown) with melt.

The arm 25 with the cooling member 26 can also be horizontally swivelledin the direction of the double arrow 37 (FIG. 2), so that operationsnear the casting nozzle 18, e.g., replacing of moulds or similar, arenot hampered. To achieve this horizontal motion a bevel gear pinion 32is connected to the pivot 31 and cooperates with a further bevel gearpinion 33 which can be turned in any desired direction by a motor 34.Such a sideswivelled position of the cooling member 26 is shown in FIG.2 with dashed and dotted lines.

If there is adamage or a leakage at the stopper 6, at

I the nozzle 8, at the wall 35 separating the supply chamber 2 from theequalization chamber 9, at the casting nozzle 18 or at the support 36,the cooling member 26 is brought into the position shown will full linesin FIG. I by swivelling the arms 23, 25. In this position the coolingmember 26 closes the casting nozzle 18 and by its cooling effectproduces a solidification of the melt in the casting duct 28 of thecasting nozzle 18. Since the cooling member 26 has a plate 26" carryingthe protrusion 27, it extends also over the support of the castingnozzle 36, so that, if a suitable size of the cooling member 26 or itscooling system is provided for, the cooling effect can be extended tothe zone or area in the vicinity of the casting nozzle 18, particularlyto the support of the casting nozzle 36, so that the melt, which mightflow out of leakage gaps in this zone or area, is also solidified. Nowthe stopper rod 5 can be exchanged without any further difficulties,which exchange is facilitated through the rcmovable connection betweenthe stopper rod 5 and the stopper support 10. In the case of a leakage,however, the melt in the supply chamber 2 can be drained off directly orindirectly through the equalization chamber 9, after solidification ofthe melt in the casting nozzle 18 without any risk of damage to theplant or the personnel. After the melt has been drained off, thenecessary repair work can be carried out.

If the machine is to be put into operation again, the cooling member 26is brought into the position 25' shown with dotted lines in FIG. 1, andis swivelled to the side, if necessary, by swivelling the arms 23 or 25,respectively. The cooling of the casting nozzle 18, which is effected bythe cooling fluid flowing through the channel 20 is interrupted, so thatthere is no longer any cooling effect on the casting nozzle 18 at all.The solidified melt in the casting nozzle 18 is reliquified by heating.For this purpose, it is useful to cover the casting nozzle 18 as well asthe surrounding region of the casting nozzle support 36 with heatinsulating material, e.g., asbestos. If necessary, the electric heatingwires in the channel 20 can be energized or the solidified melt plug inthe duct 28 can be liquified from above by means of an oxygen flame, orthe plug of the solidified melt can be mechanically removed.

Of course it is also possible to use cool air as a cooling agent, e.g.,which is conducted through the conduits 20 of the casting nozzle 18.Extreme freezing agents, particularly inert gases, e. g., liquidnitrogen, helium or CO can also be used. In all cases in which liquid orgasous cooling agents are used, it is advisable to employ this coolingagent in a closed system, e.g. pipes or tubes, to prevent the formationof inflammable gases. This closed cooling system can be formed by thechannels 20 leading to the casting nozzle 18 and/or by the system in thecooling member 26 connected to the conduits 29, which may be formed byhoses.

Of course the invention can also be used in casting plants in which theequalization chamber 17 is partly or entirely situated within the supplychamber 1 and is at least partly surrounded by the melt contained in thesupply chamber.

I claim:

1. A process for the emergency interruption of the flow of melt in agravity-type casting plant having a supply chamber,

an upwardly directed casting nozzle spaced from said supply chamber andhaving an outlet opening, control means for controlling the flow of meltunder its own weight from the supply chamber to the cast ing nozzle anddamming up the melt in the supply chamber to a higher level than thelevel of the outlet opening of the casting nozzle, comprising the stepsof temporarily closing the casting nozzle from above,

and then forming a plug in the casting nozzle by cooling the melt atleast in the region of said casting nozzle until said melt is solidifiedin said region and thereby interrupts the flow of melt through thecasting nozzle independently of said control means and avoids undesiredoverflow of the melt.

2. The process of claim 1, wherein the step of damming up the melt inthe supply chamber by cooling the region of the casting nozzle comprisesthe placing of a cooling member on the casting nozzle and holding thecooling member on the casting nozzle until at least the melt in theregion of the mouth of said casting nozzle is solidified and forms aplug.

3. The process of claim 1, wherein upwardly directed passageway meansform a support for said casting nozzle and wherein the step of coolingthe melt in the re- 3,828,974 7 8 gion of the casting nozzle includesthe step of cooling tween the control means and casting nozzle. theCasting nozzle Support around the passageway 5. The process of claim 1,including the step of reesmeans.

4. The process of claim 1 including the p of q tabllshlng the flowthrough said cooling nozzle by meltizing the level between said controlmeans and said ing the P thereincasting nozzle by flowing the melt inthe region be-

1. A process for the emergency interruption of the flow of melt in agravity-type casting plant having a supply chamber, an upwardly directedcasting nozzle spaced from said supply chamber and having an outletopening, control means for controlling the flow of melt under its ownweight from the supply chamber to the casting nozzle and damming up themelt in the supply chamber to a higher level than the level of theoutlet opening of the casting nozzle, comprising the steps oftemporarily closing the casting nozzle from above, and then forming aplug in the casting nozzle by cooling the melt at least in the region ofsaid casting nozzle until said melt is solidified in said region andthereby interrupts the flow of melt through the casting nozzleindependently of said control means and avoids undesired overflow of themelt.
 2. The process of claim 1, wherein the step of damming up the meltin the supply chamber by cooling the region of the casting nozzlecomprises the placing of a cooling member on the casting nozzle andholding the cooling member on the casting nozzle until at least the meltin the region of the mouth of said casting nozzle is solidified andforms a plug.
 3. The process of claim 1, wherein upwardly directedpassageway means form a support for said casting nozzle and wherein thestep of cooling the melt in the region of the casting nozzle includesthe step of cooling the casting nozzle support around the passagewaymeans.
 4. The process of claim 1, including the step of equalizing thelevel between said control means and said casting nozzle by flowing themelt in the region between the control means and casting nozzle.
 5. Theprocess of claim 1, including the step of reestablishing the flowthrough said cooling nozzle by melting the plug therein.